Estimation of Urban Street Segment Travel Time Using Buses as Real-Time Speed Probes

Transit buses could be used as general traffic probes in developing urban arterial performance measures. Past bus probe studies are focused on either highway applications or using the so-called archived automatic vehicle location (AVL) bus data, which is not truly useful in advanced traveler information system (ATIS) type applications. As one of the first of its kind, this study applies real-time AVL bus data to infer general vehicle traffic conditions on a signalized street. Exploratory analyses of both real-time AVL bus and general vehicle traffic data reveal bus-car speed relationships are location specific and exhibit rational patterns at different locations. Two types of statistical models, linear regression and state space model, are able to quantify the observed bus-car relationships and produce reasonable speed and travel time estimates for general vehicles, showing the real-time AVL bus probe idea is at work. Further research is underway to fully realize the real-time AVL bus probe idea on urban signalized streets.